ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Colorimetric determination of the end point in titration of tannins by the L.ovrddot.owenthal method

V. Zitko

Slovak Academy of Sciences, Bratislava

Abstract: A modification of the colorimetric detn. of the end point in the titration of tannins by the Loewenthal method (Smit, et al., C.A. 49, 15114a) is described. The relation of the extinction measured by the filter IF 465 to ml. of added 0.1N KMnO₄ in the vicinity of the end point (corresponding to a change from green to yellow) has the shape of 2 lines crossing in the end point. Before reaching the end point the extinction decreases linearly with addn. of KMnO4 and does not change after the end point with addnl. KMnO₄. The colorimetric detn. of the end point gives 1/3 the error of the visual titration. The linear relation of KMnO4 consumption to tannin concn. in the interval 0-7 mg./100 ml. is expressed by the equation V = 0.242T + 0.416; V is ml. 0.1N KMnO₄ and T is mg. tannin.

Full paper in Portable Document Format: 129a533.pdf (in Slovak)

Chemical Papers 12 (9) 533–542 (1958)